Search Results (233)

Hepatocellular carcinoma (HCC) is the most common type of liver cancer that is mostly preceded by cirrhosis, with a high mortality rate. Therefore, diagnosis is critical in the early stages. In this study, we explored the liver expression of metabotropic glutamate receptor 3 (mGluR3), a group II mGluR, during the progression from fibrosis to cirrhosis and, ultimately, to HCC induced by diethylnitrosamine (DEN) in rats. We found that mRNA expression of mGluR3 (Grm3) was upregulated in HCC, while the protein level was significantly increased from the cirrhosis stage, and even more in HCC. Grm3 correlated with interleukin-6 (Il6) and transforming growth factor-β (Tgfb) mRNA expression. Furthermore, serum and intrahepatic glutamate concentrations were augmented in HCC. Immunohistochemical analysis revealed that mGluR3 is expressed in hepatocytes and non-parenchymal cells (endothelial cells and macrophages), and we observed a positive signal in the cytoplasmic membrane, cytoplasm, and nuclei of tumor and non-tumor cells. We confirmed that normal hepatocytes (C9 cell line) express low levels of mGluR3 protein and HCC-derived cells (HepG2) express high levels of this receptor. Using HepG2 cells, we observed that mGluR3 activation by glutamate and the group II-selective agonist LY354740 treatments were functional, as both inhibited cAMP generation induced by forskolin and increased cellular viability with no effect on dead cells. These results showed that mGluR3 is differentially expressed throughout the progression of liver pathologies, is associated with the inflammatory environment, and plays a role in HCC cell survival, with potential utility as an early biomarker and therapeutic target. Full article

Glutamate metabotropic receptors (mGluRs) and their molecular partners at the postsynaptic density (PSD) represent a highly dynamic molecular hub that integrates multiple neurotransmitter signals and regulates synaptic plasticity and metaplasticity, which are putatively involved in the pathophysiology of psychiatric illnesses, including schizophrenia. Group I mGluRs (mGluR1 and mGluR5) interact with PSD adaptor and scaffolding proteins, such as Homer, Shank, Norbin, and PICK1, as well as intracellular downstream effectors, creating a molecular network that resembles a Lego-like structure, where modular protein interactions fine-tune glutamatergic transmission. Evidence from preclinical research indicates that dysregulation of mGluR expression and function, along with disrupted PSD protein expression, may contribute to the pathophysiology of schizophrenia by altering glutamatergic neurotransmission and synaptic stability. Antipsychotic mechanisms of action may involve, at least in part, the modulation of mGluR activity mediated through PSD proteins. Notably, novel agents that enhance spinogenesis by acting at the level of PSD proteins, such as SPG302, may open promising avenues for therapeutics aimed at restoring synaptic integrity. While Group I mGluRs dominate postsynaptic regulation, Group II (mGluR2/3) and III (mGluR4/6/7/8) receptors -primarily presynaptic- inhibit neurotransmitter release and plasticity, offering complementary therapeutic avenues. Emerging strategies, such as allosteric modulators of mGluRs, aim to rebalance synaptic signaling in treatment-resistant schizophrenia. This review synthesizes how PSD proteins and mGluRs interact in schizophrenia, exploring their potential as druggable targets for novel therapies. Full article

The incidence and mortality rates of lung adenocarcinoma (LUAD) continue to rise, highlighting an urgent need for novel therapeutic targets. In this study, bioinformatics analysis revealed that members of the metabotropic glutamate receptor (mGluR) family are significantly correlated with the expression profile, prognosis, genetic mutations, and tumor immune microenvironment of LUAD, with GRM5 being the most significantly associated member. Overexpression of GRM5 has been shown to inhibit LUAD proliferation and induce apoptosis, while cinchonine (CN) treatment further enhances these effects, suggesting that CN may act as a GRM5 agonist to synergistically exert antitumor activity. Transcriptome sequencing further identified four key downstream targets and their associated signaling pathways. In summary, this study confirms that GRM5 can serve as a potential prognostic biomarker and therapeutic target for LUAD, while the small-molecule compound CN shows promise as an antitumor candidate drug targeting GRM5. Full article

Background/Objectives: Anti-mGluR1 encephalitis is a rare form of autoimmune encephalitis predominantly manifesting as acute/subacute cerebellar ataxia. We describe a newly diagnosed case series from our center and conduct a comprehensive review of reported cases worldwide to compare clinical manifestations, treatment options, and outcomes. Methods: We consecutively identified 11 patients at Peking Union Medical College Hospital, and additionally extracted clinical data from 42 previously published cases identified via PubMed and Google Scholar (search updated to 1 August 2025). Demographics, phenotypes, laboratory findings, imaging, treatment, and outcomes were systematically summarized. This pooled review was not prospectively registered, and extracted data from 21 published articles were analyzed alongside our 11 newly diagnosed cases. Results: The integrated cohort comprised 53 patients with anti-mGluR1 encephalitis, including 29 males and 24 females, with patients reported from Asia (n = 18), North America (n = 11), and Europe (n = 24). The median age at onset was 50 years (IQR 29.5–58.5; range 3–81), with North American patients presenting later than their Asian and European counterparts (median 60 vs. 48 and 45 years, respectively; all p < 0.05). Disease onset was subacute in most cases (58.7%). Comorbid tumors were present in nine patients, most commonly lymphomas. Clinical phenotypes were classified as pure cerebellar syndrome (n = 31), cerebellar ataxia with encephalitic features (n = 20), and non-cerebellar presentations (n = 2). Baseline severity differed across phenotypes (χ² = 35.7, p < 0.001). Regional variability in severity was observed but did not reach significance. CSF analyses revealed pleocytosis in 59% (23/39), elevated protein in 31.3% (5/16), and oligoclonal bands in 52.2% (12/23). MRI abnormalities were detected in 34.7% (17/49) of patients, with 21.9% (7/32) developing cerebellar atrophy on follow-up. Therapeutic strategies varied significantly across regions (p = 0.041), with Asian cohorts more frequently receiving long-term immunosuppression, European cohorts favoring combined regimens, and North American cases relying predominantly on first-line therapies. Overall, 65.9% (29/44) of patients clinically improved, 13.6% (6/44) relapsed and 20.5% (9/44) remained unaffected. Conclusions: Anti-mGluR1 encephalitis presents with significant clinical heterogeneity, ranging from cerebellar-dominant ataxia to neuropsychiatric or non-cerebellar phenotypes, and demonstrates differences in reported age of onset, disease severity, and therapeutic approaches across publication regions. Our findings underscore the importance of early recognition, sustained immunotherapy, and international collaboration to establish standardized, evidence-based management for this rare but disabling disorder. Full article

Aspergillus flavus and its aflatoxins pose serious threats to human and animal health, negatively affecting agricultural productivity and the global economy. Although chemical preservatives are widely used, their effectiveness remains limited by increased fungal resistance and environmental concerns, highlighting the need for sustainable alternatives. Microbial volatile organic compounds (mVOCs) represent a promising biocontrol strategy. Here, we investigate how glutamine regulates mVOC biosynthesis in Streptomyces alboflavus TD-1 and enhances its antifungal activity against A. flavus. Antifungal assays showed that supplementation with 40 mM glutamine significantly enhanced inhibitory activity, leading to 69.0% inhibition of conidial germination and 64.5% inhibition of mycelial biomass. Transcriptome profiling identified 283 differentially expressed genes, including the two-component system regulator gluR, which was strongly upregulated. CRISPR/Cas9-mediated disruption of gluR confirmed its regulatory role. Specifically, the mutant strain produced reduced levels of antifungal mVOCs, such as dimethyl trisulfide and o-anisidine, and exhibited diminished inhibition of A. flavus. Collectively, these findings demonstrate that exogenous glutamine enhances the mVOC-mediated suppression of A. flavus by S. alboflavus TD-1 through nutrient-sensing and transcriptional regulation of volatile biosynthesis. Although aflatoxin levels were not quantified in this study, the enhanced growth inhibition and the identified mVOC shifts provide a mechanistic basis for future studies that directly quantify aflatoxin production under storage-relevant conditions. Full article

Growing evidence has revealed that gut dysbiosis is associated with the development of anxio-depressive disorders through mechanisms that involve neuroimmune signaling, neurotransmitter changes, and neuroplasticity in the brain. This study investigated the effects of gingerol-enriched ginger (GEG) on specifically anxiety-related neuroinflammation-, neuroimmunity-, neuroplasticity-, neurotransmission-, and neurotoxicity-associated genes in different brain regions, as well as on alterations linked to colonic microflora-driven dysbiosis, in the spinal nerve ligation (SNL) rat model of neuropathic pain (NP). Twenty-seven male rats were assigned to 3 groups: sham, SNL, and SNL-treated with GEG at 200 mg/kg body weight (SNL+200GEG) via oral gavage for 5 weeks. Anxiety-like behavior was assessed on the elevated plus maze (EPM). mRNA expression was assessed by qRT-PCR using respective primers. Correlation between behavioral parameters and colonic microbiome composition was analyzed using the Spearman rank correlation. The SNL+200GEG group demonstrated decreased anxiety-like behavior in the SNL model. Compared to the SNL group, the SNL+200GEG group had increased mRNA expression of NRF2 (amygdala: left), LXRα (amygdala: both sides), and CX3CR1 (amygdala: both sides, hippocampus: right). GEG modulated neuroplasticity as shown by increased gene expression of PGK1 (amygdala: right, hippocampus: both sides), MEK1 (frontal cortex: both sides), LDHA (frontal cortex: both sides), GPM6A (frontal cortex: both sides, amygdala: right, hippocampus: right, and hypothalamus), and GLUT1 (amygdala: right) as well by decreased gene expression of HIF1α (in all brain regions except for the hypothalamus). GEG modulated neurotransmission via clearance of excessive glutamate release as suggested by increased gene expression of SLC1A3 (frontal cortex: both sides, hippocampus: right) and via augmenting mGluR5 signaling as shown by increased gene expression of GRM5 (hippocampus: both sides, hypothalamus) as well as downregulation of KMO, HAAO, GRIN2B, and GRIN2C influencing downstream serotonergic neurotransmission and NMDA receptor-mediated glutamatergic pathways in different brain regions. GEG further alleviated neurotoxicity through downregulated gene expression of SIRT1, KMO, IDO1, and HAAO in different brain regions. Moreover, the increased relative abundance of Bilophila spp., accompanied by decreased time spent in the EPM open arms, suggests that increased Bilophila abundance increases anxiety-like behavior. GEG supplementation mitigated anxiety-like behavior in male rats with NP, at least in part, by reducing SNL-induced inflammatory sequelae-related mRNA gene expression in different brain regions. In addition, there is a positive correlation between the abundance of Bilophila wadsworthia and the degree of anxiety-like behavior. Full article

Astrocytes are increasingly recognized as active participants of synaptic communication, yet their role in the basal ganglia circuitry remains poorly defined. Emerging evidence indicates that astrocytes in this region express a diverse array of neurotransmitter receptors thought to regulate intracellular calcium signaling, gliotransmitter release, synaptic plasticity, and neuroimmune responses. However, the literature is limited by methodological variability and a pronounced focus on the striatum, with comparatively little data on other basal ganglia nuclei. This review aims to organize the current literature on astrocytic receptor systems within the basal ganglia, including dopaminergic (D1–D5), glutamatergic (AMPA, NMDA, mGluRs), GABAergic (GABA-A, GABA-B), purinergic (P1, P2), and adrenergic (α, β) receptors. By organizing receptor-specific findings across basal ganglia structures, this review provides a foundation for future investigations into astrocytic function in this complex neural network. Full article

Glutamine addiction in human melanoma is a premier example of the cancer hallmark of metabolic reprogramming. In the present study, we investigate the presence of metabotropic glutamate receptor 1 (mGluR1/GRM1) and glutaminase (GLS1/GLS) in canine oral malignant melanoma (OMM) and those of low malignant potential, termed histologically well-differentiated melanocytic neoplasm of the lips and oral mucosa (HWDMN). We used immunohistochemistry (IHC) and qPCR to evaluate mGluR1 and GLS1 protein expression and RNA expression, respectively. Nearly 20% of OMM cases had an mGluR1 IHC score ≥ 1, while none of the HWDMN cases had any expression. Due to low IHC expression, only 10 cases were selected for determination of GRM1 RNA expression, and none were positive. GLS RNA expression did not differ between OMM and HWDMN. A GLS1 IHC score ≥ 1 was significantly higher in OMM cases and highly specific (95%) for correctly identifying tumors with a Ki67 index ≥ 19.5. These results may have been negatively impacted by use of a brown chromogen for IHC labeling among background pigment, particularly in HWDMN. Ultimately, these findings suggest that canine OMM does not heavily rely on mGluR1 for tumorigenesis or progression. Differential GLS1 protein expression warrants further investigation with protein quantification. Full article

Febrile seizures (FS) are a common childhood neurological event associated with an increased risk of long-term cognitive and emotional deficits, though the precise mechanisms remain elusive. Using a rat model, we investigated the long-term effects of FS induced on postnatal day 10, assessing outcomes in young adulthood (P45-55). We report region-specific neuronal loss in the hippocampus, more extensive in the ventral segment. Molecular analysis revealed a broad downregulation of genes encoding ionotropic and metabotropic glutamate receptors and excitatory amino acid transporters. These alterations were most severe and persistent in the ventral hippocampus and medial prefrontal cortex. Behaviorally, rats with neonatal FS exhibited a hyperanxious phenotype, characterized by reduced locomotor and exploratory activity and impaired habituation to a novel environment. In contrast, spatial working memory and social behavior remained intact. Our results provide the first comprehensive evidence that neonatal FS trigger long-term, region-specific disruptions of the glutamatergic system within hippocampal–prefrontal circuits. These findings identify vulnerable molecular targets and precise neurobiological mechanisms that may underlie the heightened risk of anxiety-related disorders following early-life FS, suggesting new avenues for therapeutic intervention. Full article

Extensive research has focused on developing anti-nociceptive therapy by targeting specific molecular pathways. Among these, the serotonin 2A receptor (5-HT2AR) and metabotropic glutamate receptor 5 (mGluR5) are recognized as key mediators of neuropathic pain. However, the therapeutic potential of their simultaneous inhibition remains largely unexplored. In this study, we evaluated the efficacy of dual antagonism of 5-HT2AR and mGluR5 using spinal nerve ligation (SNL) and formalin-induced pain models in male Sprague–Dawley rats. Co-administration of selective antagonists significantly enhanced anti-allodynic and anti-nociceptive effects, as evidenced by increased withdrawal thresholds and reduced pain-related behaviors compared to monotherapy. The analgesic efficacy of dual antagonism was comparable to that of gabapentin and morphine. Additionally, novel small molecules designed to concurrently inhibit 5-HT2AR and mGluR5 exerted dose-dependent anti-nociceptive effects by suppressing excitatory postsynaptic responses and inhibiting the phosphorylation of ERK and AKT signaling molecules. Importantly, unlike morphine, repeated administration of the dual antagonist maintained anti-allodynic efficacy with a low potential of abuse. These findings may indicate the promise of simultaneous 5-HT2AR and mGluR5 antagonism as a novel and potentially safer strategy for managing chronic neuropathic pain. Full article

Feline calicivirus (FCV) is among the few members of the Caliciviridae family that can replicate efficiently in vitro. Our recent studies have found the Transferrin Receptor Protein (TFRC) is an entry receptor that facilitates the internalization of FCV. To explore the potential involvement of additional host factors in conjunction with TFRC during the viral entry process, we identified metabotropic glutamate receptor 2 (mGluR2) as a specific interacting partner for both TFRC and the FCV VP1 protein by Co-IP analysis. Our findings indicate that the downregulation of mGluR2, along with its downstream signaling molecule, Calcium-activated potassium channel subunit alpha-1 (KCa1.1), significantly inhibits FCV replication by impairing viral internalization. Importantly, the knockout of TFRC did not diminish the effects of mGluR2 and KCa1.1 on FCV infection. Furthermore, mGluR2 was found to interact directly with FCV VP1, rather than with TFRC, and the rate of F-actin polymerization induced by FCV infection was reduced solely by the downregulation of mGluR2 protein expression, not by TFRC knockout. These results suggest that mGluR2 may independently mediate FCV internalization, operating independently of TFRC, and plays a critical role in the formation of endocytic vesicles. Overall, the results indicate that multiple host factors, including TFRC and mGluR2, are involved in the internalization of FCV into host cells. Further research is necessary to explore the propagation of other caliciviruses, such as norovirus, in vitro. Full article

In our previous study, we demonstrated that a standardized ethanol extract of Perilla frutescens var. acuta (PE) alleviates memory deficits in an Alzheimer’s disease mouse model by inhibiting amyloid β (Aβ) aggregation and promoting its disaggregation. However, the extent to which PE exerts additional cognitive benefits independent of Aβ pathology remained unclear. Here, we aimed to evaluate the effects of PE on synaptic plasticity and learning and memory functions. Male ICR mice were used, and cognitive impairment was induced by scopolamine administration. PE was orally administered at doses determined from previous studies, and cognitive performance was assessed using the passive avoidance, Y-maze, and Morris water maze tests. In parallel, hippocampal slices were employed to examine the effects of PE on synaptic plasticity. PE (100 and 300 μg/mL) significantly enhanced long-term potentiation (LTP) in a concentration-dependent manner without altering basal synaptic transmission. This facilitation of LTP was blocked by scopolamine (1 μM), a muscarinic acetylcholine receptor (mAChR) antagonist, and IEM-1460 (50 μM), a calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (CP-AMPAR) inhibitor, indicating the involvement of mAChR and CP-AMPAR pathways. In vivo, PE (100, 250, and 500 mg/kg) treatment improved memory performance across all behavioral tasks and upregulated hippocampal synaptic proteins including GluN2B, PSD-95, and CaMKII. Collectively, these results demonstrate that PE ameliorates scopolamine (1 mg/kg)-induced cognitive impairment by enhancing synaptic plasticity, likely through modulation of mAChR, CP-AMPAR, and NMDA receptor signaling. These findings highlight the therapeutic potential of PE for memory deficits associated with cholinergic dysfunction. Full article

Background and Objective: Humanized models of Alzheimer’s disease (AD) provide valuable tools for investigating the mechanisms of this neurodegenerative disorder, the leading cause of dementia. These models enable the study of AD progression and the potential disease-modifying properties of drugs or dietary nutrients delivered through nutrition. Here, we examine molecular markers of metabolic and synaptic dysfunction in the hippocampus of 6-month-old 3×Tg-AD mice and assess whether a dietary insulin sensitizer can delay synaptic decline. Methods: First we characterized the molecular phenotype of 3×Tg-AD at 12 months using shotgun proteomics and phosphoproteomics to assess metabolic and synaptic changes in the hippocampus. Then, we characterized the effects of early daily oral D-chiro-inositol (DCI, Gyneos^®) for three months, starting at 3 months of age, to test restoration of insulin signaling and glutamatergic synaptic markers. To this end we evaluated a) insulin signaling pathway components (insulin receptor, IRS1, PI3K, AKT, GSK3β) at mRNA, protein, and phosphorylation levels, and b) the expression of glutamate receptors (mGluR5, GluR1, GluR2, NMDAR1, NMDAR2A, NMDAR2B). Sex effects were explored. Results: 12-month 3×Tg-AD mice exhibit metabolic and synaptic dysfunction in the hippocampus, with phosphoproteomic changes suggesting altered glutamatergic synapses. At 6 months, disruptions in insulin signaling were evident, including altered expression and phosphorylation of insulin pathway components, and changes in glutamate receptor subunits. Early DCI treatment largely reversed these alterations. Several effects showed sex dependency. Conclusions: Early insulin-sensitizing intervention via DCI can restore insulin signaling and counteract hippocampal synaptic impairments in this AD model, supporting the potential for nutrient-based strategies to delay synaptic decline. Sex differences underscore the need to tailor therapeutic approaches in modifying AD progression. Full article

The study assesses the relationship between thalamic proton-MR spectroscopy (¹H-MRS) metabolites and thalamic ¹¹C-ER176 translocator-protein positron emission tomography (TSPO-PET) standardized uptake value ratios (SUVR) to advance our understanding of thalamic involvement in multiple sclerosis (MS)-associated neurodegeneration and disability. In this prospective cross-sectional study, patients with MS (pwMS) and controls underwent 3T-MRI, ¹H-MRS, and ¹¹C-ER176-PET targeting the thalamus. MRI-derived thalamic volume was normalized by intracranial volume. ¹H-MRS metabolites—N-acetylaspartate (NAA), glutamate (Glu), glutamine (Gln), total choline (tCho), and myo-inositol (mIns)—were normalized to total creatine (tCr). Clinical disability was evaluated using MS-specific tests of Expanded Disability Status Scale-EDSS and MS-functional composite-MSFC (including Paced Auditory Serial Addition Test-PASAT). Compared to controls (n = 30), pwMS (n = 21) exhibited smaller thalamic volume, higher thalamic ¹H-MRS mIns/tCr (putative gliosis marker), and higher thalamic ¹¹C-ER176-PET SUVR (glial density marker). In pwMS, higher thalamic mIns/tCr (r = −0.67) and tCho/tCr (r = −0.52) correlated with smaller thalamic volume. In pwMS, higher thalamic mIns/tCr correlated with higher thalamic ¹¹C-ER176-PET SUVR (r = 0.48) and decreased cognitive function (PASAT, rho = −0.48). In controls, decreased thalamic NAA/tCr correlated with increased thalamic ¹¹C-ER176-PET SUVR (r = −0.41). Thalamus, a core central nervous system relay, is affected early in MS disease course. Glial-mediated innate immune activation in the thalamus, evaluated by increased ¹H-MRS mIns/tCr and ¹¹C-ER176-PET SUVR, is associated with loss of thalamic volume and increased disability in pwMS. The multimodal imaging approach with ¹H-MRS mIns/tCr and ¹¹C-ER176-PET SUVR emerges as potential glial biomarkers, to better understand disease mechanisms and evaluate therapeutic interventions targeting glial activity in MS. Full article

The bidirectional relationship between epilepsy and depression illustrates shared neurobiological mechanisms of neuroinflammation, hypothalamic–pituitary–adrenal axis dysregulation, and glutamatergic dysfunction. Depression is present in 20–55% of people with epilepsy, far greater than in the general population, while depression doubles epilepsy risk 2.5-fold, indicating shared pathophysiology. Neuroinflammatory mediators (interleukin-6, tumor necrosis factor alpha, high-mobility group box 1) establish a vicious cycle: seizures exacerbate inflammation and mood disruption, and stress lowers seizure thresholds. Hippocampal damage and cortisol toxicity also link these disorders, with early life stress imprinting lifelong risk via epigenetic alteration. Genetic studies identify pleiotropic genes (brain-derived neurotrophic factor) that regulate synaptic plasticity, serotonin activity, and immune responses. New treatments target shared pathways: ketamine and AMPAkines normalize glutamate tone; mGluR5 antagonists attenuate hyperexcitability and inflammation; DNA methyltransferase inhibitors reverse aberrant DNA methylation; and probiotics manipulate the gut–brain axis by boosting neuroprotective metabolites like butyrate. Despite challenges—transient effects, precision dosing, and blood–brain barrier penetration—these advances constitute a paradigm shift toward mechanistic repair rather than symptom management. The way forward includes clustered regularly interspaced short palindromic repeats (CRISPR)-based epigenome editing, biomarker-led therapies, and combination approaches (e.g., ketamine and probiotics). Such comorbidity needs to be managed holistically through integrated neuropsychiatry care, offering hope to patients with treatment-refractory symptoms. Full article